My wife was born in December so I am looking to get her a matching blue gemstone earring and necklace for Christmas. Is topaz my best choice? What are some recommended online vendors? I did a search through several vendors and price vary ALOT. I learned how to price out diamonds here...is it about the same for gemstones? Sorry for all the noob questions but this is my first time purchasing a gemstone. Budget is $1,000.